. >>> condolences from bill clinton to spike lee. social media lights up as the famous and not so famous share their thoughts. >>> the storm warnings across the middle of the nation as ice and snow, extreme arctic cold make for a miserable morning. it is friday, december 6th. >> announcer: from abc news, this is "world news now" with john muller and diana perez. >> we begin with the death of a man who changed the world, former south african president nelson mandela passing away at the age of 95. >> there's mourning and respectful celebration at every corner of the globe as millions honor mandela's legacy. his fight for racial equality landed him in prison for nearly three decades. he emerged undeterred and unbroken. abc's alexander marquardt has more. >> reporter: south africa has entered a period of national mourning. profound sadness at the loss of a man many affectionately knew as tata madiba. his death was announced by jacob zuma, who called mandela south africa's greatest son. the celebration has been remarkable. people of all s